The work proposed here is composed of two distinct but related studies making full use of an established preparation for collecting spermatozoa and fluid from the testis of conscious rams. The objectives of this proposal are: 1) to determine factors affecting sperm maturation by studying the metabolism, composition, enzymic activity, motility and fertilizing ability of ram testicular spermatozoa after storage in vitro under controlled conditions with the ultimate goal of developing an "artificial epididymis"; 2) to investigate the control mechanism involved in steroid secretion of the testis by measuring testosterone, androstenedione, dihydrotestosterone and estradiol-17 beta levels in rete testis fluid (RTF) and peripheral blood plasma (PBP) of conscious rams before and after i.v. injection of follicle stimulating hormone (FSH) or luteinizing hormone (LH) or LH plus FSH; 3) to study the effects of LH and FSH on the metabolic activity of testicular spermatozoa and developing germinal cells and on the concentration of certain RTF constituents related to the activity of the seminiferous epithelium. We anticipate that such an in vitro system for promoting the development of the fertility ability of spermatozoa would be useful in evaluating the mode of action of existing or future post-testicular antifertility agents. Further, our proposed studies on the endocrine function of the testis will enhance our knowledge on the testis-hypo-physeal axis and may suggest new approaches for development of new, and delivery of known, antifertility compounds which inhibit the formation of spermatozoa in the testis or cause damage to developing germinal cells.